Slag removal method during thermochemical scarfing



April l, 1969 i lfP. THOMPSON SLAG REMOVAL METHOD DURING THERMOCHEMICAL SCARFING Filed May 19, 1966 F l G. I

INVENTOR. VAN P. THOMPSON A r l PLwm/mm ATTORNEY United States Patent 3,436,276 SLAG REMOVAL METHUD DURING THERMOCHEMICAL SCARFING Ivan P. Thompson, Hillside, NJ., assignor to Union Carbide Corporation, a corporation of New York Filed May 19, 1966, Ser. No. 551,367 Int. Cl. B231: 7/00 U.S. Cl. 14S-9.5 3 Claims This invention relates to a method for scarling the surface of a metal body, and more particularly to improvements on a method of trapping and disposing of the molten slag produced upon the surface of the metal body during the thermochemical reaction, by the use of a fluid stream which is discharged so as to skim across the surface of the body at high velocity.

The basic method for trapping and removing slag produced during scarng is disclosed by I. P. Thompson et al. in U.S. Patent 2,465,297. As disclosed therein, during the thermochemical scarfing process a stream of oxidizing gas is directed obliquely against a reaction zone of molten metal which has previously been formed upon the surface of the body. By so doing, a thermochemical reaction is produced, which continues longitudinally along the surface =of the body as relative movement is produced between the body and the stream of oxidizing gas. As a result of this thermochemical scarfing reaction, a molten slag is produced which must be removed from the surface of the Ibody. This is accomplished accord-ing to Thompson et al. by directing a stream of fluid, e.g. water, at high velocity, in such manner as to skim across the surface of the body and thereby impinge against and deflect and remove the slag olf the surface thereof. The liuid stream also breaks the slag into small particles, chills them, and carries them from the body surface into a slag chute.

While the Thompson et al. method has been used successfully for many years, it is not entirely satisfactory since it fails to trap the fine spray of slag particles that are deflected from the main lluid stream, as well as from the reaction itself. A certain portion of the slag particles also penetrates through the fluid stream due to their momentum. In addition, a considerable quantity of slag spray is deflected in directions away from the slag chute, causing a substantial buildup and accumulation of slag upon the scarfing machine, slag target, roll table and smoke hood. Such buildup of slag necessitates frequent maintenance and consequently causes downtime of the machine.

It is the principal object of this invention to provide an improved method of trapping and removing slag produced during a thermochemical scarfing reaction, such that subtantially all of the slag produced will be removed from the scarfed body, with little, if any, being deflected against the surfaces of the scarfing machine, slag target, roll table, smoke hood and other parts of the work area.

According to the present invention, a deflector surface is positioned across the path of relative movement of the body to be scarfed, at a point adjacent the reaction zone, and in the path of the slag produced. A fluid stream, e.g. water, is then flowed upon the surface of the .ice

deflector in order to maintain it wetted. The effect of the wetted deflector surface is remarkable in that the particles of flying slag which strike the surface do not stick to it. Instead they are immediately solited and washed over the dellector surface into a slag chute. Moreover, the surface prevents the slag particles from penetrating through the fluid stream and escaping into the work area. While the deector may be dat, when scarling relatively wide metal bodies it is preferable to have it curve shaped, with the cavity thereof facing the reaction zone.

In the drawing:

FIGURE 1 is an isometric elevational view of a metal body being scarfed, illustrating a preferred embodiment of the invention, utilizing a wetted curve shaped dellector and FIGURE 2 is an isometric elevational view similar to FIGURE 1, but illustrating another embodiment of the invention, utilizing a flat dellector surface.

Referring to FIGURE l, the metal body to be scarfed is supported upon and moved by roll table R toward a scarling unit M. A molten puddle of metal is formed upon the surface of the body at reaction zone Z, by preheat iiames from the scarling unit M. Thereafter a sheet-like stream of oxidizing gas S, e.g. oxygen, is dithermochemical reaction. Relative movement is then rected obliquely against the molten puddle to cause a thermochemical reaction. Relative movement is then produced between the metal body W and the oxidizing gas stream S so as to continue the reaction longitudinally along the surface of the body. As the scarling reaction proceds, molten slag is produced and projected forwardly and upwardly from the reaction zone Z, as shown generally by the arrows.

In order to trap and remove the slag which is produced, a surface 12 is positioned across the path of relative movement at a point adjacent the reatcion zone Z and in the path of the projected slag. A stream of fluid, e.g. water, is owed at high velocity over the surface 12 in order to maintain the same wetted continuously.

As the particles of molten slag strike the wetted deilector surface they are immediately chilled, solidified, and washed along the wetted surface area into a slag chute 14. The surface 12 backing up the uid stream acts as a shield to prevent a portion of the projected slag from penetrating through or becoming deflected by such stream.

The surface 12 is preferably curved-shaped with the cavity therein facing the reaction zone Z. This congura- -tion is particularly effective when scarling relatively wide metal bodies, i.e. slabs, in that it forms a pocket to maintain the coherency of the lluid stream over the entire length of the surface.

The diameter of the curve-shaped surface will usually be of -the order of 6 to 12 inches, over which a llow of about 700 to 1,000 gallons of fluid per minute is maintained during scarling.

As shown in FIGURE 2, when scarng relatively narrow metal bodies, e.g. billets, at surfaces 16 may be used to back up each uid stream with good results. When scarfing a 10 inch square billet, for example, four nozzles N, each having a diameter of 1% inch and discharging 3 about 200 g.p.'m. each, were found highly effective in trapping and removing the slag produced during scarfing.

What is claimed is:

1. In a thermochemical scarfng process wherein an oxidizing `gas is directed from a scarfing unit against a reaction zone of molten metal on the surface of a metal body to produce a thermochemical reaction thereon, and relative movement is produced between such scaring unit and the body for continuing such reaction along the length of such surface, the improvement in trapping and disposing of the molten slag produced during such reaction from the scarng area which comprises: positioning a deector surface across the path of relative movement at a point adjacent the reaction zone and in the path of the slag produced, and flowing a uid stream over 1 said surface to maintain the same wetted.

4 2. In a scarng process as claimed in claim 1 wherein said surface is curved-shaped with the cavity therein facing the reaction zone.

3. In a scarfing process as claimed in claim 2 wherein said surface is maintained cool by water owing thereupon and comprising said uid stream.

References Cited UNITED STATES PATENTS 12/1964 Thompson et al 148-95 2,465,297 3/1949 Thompson et al. 14S- 9.5

L. DWAYNE RUTLEDGE, Primary Examiner.

5 W. W. STALLARD, Assistant Examiner.

'Zgggo y 'UNITED STATESPATNTOFFICE A CERTIFICATE 0F CORRECTION Y page No. 3,436,276 l ntedpril 1, 1969 Inventor) I.P. Thompson It :ls certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 2, line 4, -"solified"sl1ould read solidified Column 2, liner 25, after the word "is" cancel "'dil" and A I insert clirected olaliquely against the .molten puddle to cause a' l Column 2, line 32, "proceda" should read proceeds signed and sealed this 19th day of 06661661- 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. v ROBERT GOTTSCHALK Attestsng Officer Acting Commissioner of Patents 

1. IN A THERMOCHEMICAL SCARFING PROCESS WHEREIN AN OXIDIZING GAS IS DIRECTED FROM SCARFING UNIT AGAINST A REACTION ZONE OF MOLTEN METAL ON THE SURFACE OF A METAL BODY TO PRODUCE A THERMOCHEMICAL REACTION THEREON, AND RELATIVE MOVEMENT IS PRODUCED BETWEEN SUCH SCARFING UNIT AND THE BODY FOR CONTINUING SUCH REACTION ALONG THE LENGTH OF SUCH SURFACE, THE IMPROVEMENT IN TRAPPING AND DISPOSING OF THE MOLTEN SLAG PRODUCED DURING SUCH REACTION FROM THE SCRAFING AREA WHICH COMPRISES: POSITIONING A DEFLECTOR SURFACE ACROSS THE PATH OF RELATIVE MOVEMENT AT A POINT ADJACENT THE REACTION ZONE AND IN THE PATH OF THE SLAG PRODUCED, AND FLOWING A FLUID STREAM OVER SAID SURFACE TO MAINTAIN THE SAME WETTED. 